Thermo-responsive Graft Copolymers based on Poly(Methyl Vinyl Ether): from Synthesis to Evaluation

Recently, stimuli-responsive polymer systems have been extensively investigated because of their wide range of potential applications in medicine, biotechnology, ecology and pharmacology. The most important stimulus in these studies is temperature. Thermo-responsive polymers are hydrophilic and water-soluble at low temperatures, but separate from these solutions when the temperature is raised above a certain temperature, which is called the cloud point temperature (Tcp). This behaviour is based on the fact that the hydrophilic polymer/water interactions dominate at low temperatures, but are broken above the Tcp. Poly(methyl vinyl ether) (PMVE) was chosen for its thermo-responsive properties close to body temperature. What has emerged from this work is that the controlled/living polymerization methods developed so far eliminate the limits in the design of novel types of graft copolymers with potential applications such as drug carriers, switchable amphiphiles, mineralization templates, etc... Several synthetic concepts have been designed to graft this polymer onto hydrophilic and hydrophobic polymer backbones. For the preparation of these polymer structures, two different strategies were used, both grafting onto and grafting from approaches to attach the copolymers as nearly monodisperse side chains of controlled molecular weight. Secondly, the physical properties of these graft copolymers have been studied with a wide range of advanced characterization techniques. These new polymers have proved to have suitable thermo-responsive properties. For example, some of them have been shown to act as efficient dispersants and stabilizers for carbon black, a good model for sludge. From the industrial viewpoint, pigment or inorganic particle stabilization in water has a huge potential due to the public demand for products friendly to the environment. Potentially, they could also be used as sensors or actuators for drug delivery systems. We expect that our work could help chemists as well as non-chemists to develop new applications which could be reliably utilized in real life application

'Living' cationic copolymerization of isobutyl vinyl ether with methyl vinyl ether: copolymerization parameters and properties of the copolymers.

The copolymerization of isobutyl vinyl ether (IBVE) with methyl vinyl ether (MVE), initiated by the system 1,1-diethoxyethane/trimethylsilyl iodide/zinc iodide and conducted at 0degreesC in toluene, was found to be 'living' just as the homopolymerizations of these monomers. Monomer reactivity ratios are r(IBVE) = 1.08 and r(MVE) = 0.43. The lower critical solution temperature of polyMVE in water, situated around 37degreesC, was lowered to 10degreesC (for a 0.25 wt.-% solution) when 6 mol-% of IBVE units were introduced in copolymers of molar mass 3000 - 7000 g/mol. At higher IBVE contents, the polymers are insoluble in water at all temperatures.The copolymerization of isobutyl vinyl ether (IBVE) with methyl vinyl ether (MVE), initiated by the system 1,1-diethoxyethane/trimethylsilyl iodide/zinc iodide and conducted at 0degreesC in toluene, was found to be 'living' just as the homopolymerizations of these monomers. Monomer reactivity ratios are r(IBVE) = 1.08 and r(MVE) = 0.43. The lower critical solution temperature of polyMVE in water, situated around 37degreesC, was lowered to 10degreesC (for a 0.25 wt.-% solution) when 6 mol-% of IBVE units were introduced in copolymers of molar mass 3000 - 7000 g/mol. At higher IBVE contents, the polymers are insoluble in water at all temperatures.A